Implicit type conversion

Implicit type conversion, also known as "coercion", is an automatic type conversion by the compiler. Implicit conversions do not require any operator. They are automatically performed when a value is copied to a compatible type. In a mixed type expression, a subtype s will be converted to a supertype t or some subtypes s1, s2, ... will be converted to a supertype t (maybe none of the s{i} is of type t) at runtime so that the program will run correctly. For example: